[fix] Use negotiated content to keep tabs with original URL

extension/src/background/main.ts

@@ -32,7 +32,7 @@ import {
   observeContent,
   getAcceptRdf
 } from "../common/data";
-import { Message } from "../common/messages";
+import { Message, activateNegotiated } from "../common/messages";
 /// <reference path="./fallback.d.ts"/>
 let F = require("./fallback");
 import "chrome";
@@ -133,10 +133,18 @@ function onSendingHeaders(
   let observation = allObservations[details.tabId];
   if (observation == null || observation == undefined) return {};
   if (observation.preemptable) {
-    // this tab has been preemted
+    // this tab has been preempted
     let headers = details.requestHeaders;
     setHeader(headers, "Accept", getAcceptRdf(false));
     return { requestHeaders: headers };
+  } else if (
+    observation.negotiated != null &&
+    observation.negotiated != undefined
+  ) {
+    // this tab has negotiated content
+    let headers = details.requestHeaders;
+    setHeader(headers, "Accept", observation.negotiated.contentType);
+    return { requestHeaders: headers };
   }
   return {};
 }
@@ -189,26 +197,27 @@ function onHeadersReceived(
   observation.primaryTopic = obs.primaryTopic;
   observation.sources = obs.sources;
   observation.preemptable = obs.preemptable;
+  observation.negotiated = obs.negotiated;
   if (obs.preemptable) {
     // modify header
     let headers = details.responseHeaders;
     setHeader(headers, "Content-Type", "text/plain");
     return { responseHeaders: headers };
   }
-  // if there are still nothing, try to probe with HTTP content negotiation
+  // if there is still nothing, try to probe with HTTP content negotiation
   if (!hasDetectedData(observation)) {
+    // look for data through content negotiation
     tryNegotiateData(details.url)
       .then((source: DocumentSourceLinked) => {
+        observation.negotiated = source;
         observation.sources.push(source);
         onObservedTabUpdated(details.tabId);
       })
       .catch((reason: string) => {
         // do nothing
-        onObservedTabUpdated(details.tabId);
       });
-  } else {
-    onObservedTabUpdated(details.tabId);
   }
+  onObservedTabUpdated(details.tabId);
   return {};
 }
 
@@ -317,23 +326,51 @@ chrome.runtime.onMessage.addListener(
 
 chrome.pageAction.onClicked.addListener((tab: chrome.tabs.Tab) => {
   let observation = resolveObservationsForTab(allObservations, tab.id);
-  let url = chrome.extension.getURL(
-    "ldbrowser/index.html?target=" + encodeURIComponent(observation.url)
-  );
-  let callback = (openedTab: chrome.tabs.Tab) => {
-    allObservations[openedTab.id] = observation;
-  };
-  let promise: any = chrome.tabs.create(
-    {
-      windowId: tab.windowId,
-      index: tab.index + 1,
-      url: url,
-      active: true,
-      openerTabId: tab.id
-    },
-    callback
-  );
-  if (promise != undefined && promise != null) {
-    promise.then(callback);
+  if (observation.negotiated != null && observation.negotiated != undefined) {
+    // a dataset can be obtained through HTTP content negotiation
+    // => open a new tab with the same observations
+    let callback = (openedTab: chrome.tabs.Tab) => {
+      allObservations[openedTab.id] = observation;
+      chrome.pageAction.setPopup({
+        tabId: openedTab.id,
+        popup: chrome.extension.getURL("popup/index.html")
+      });
+      activateNegotiated(openedTab.id, observation);
+    };
+    let promise: any = chrome.tabs.create(
+      {
+        windowId: tab.windowId,
+        index: tab.index + 1,
+        url: observation.url,
+        active: true,
+        openerTabId: tab.id
+      },
+      callback
+    );
+    if (promise != undefined && promise != null) {
+      promise.then(callback);
+    }
+  } else {
+    // dataset is obtained from another source
+    // => open the linked-data browser as an extension page
+    let url = chrome.extension.getURL(
+      "ldbrowser/index.html?target=" + encodeURIComponent(observation.url)
+    );
+    let callback = (openedTab: chrome.tabs.Tab) => {
+      allObservations[openedTab.id] = observation;
+    };
+    let promise: any = chrome.tabs.create(
+      {
+        windowId: tab.windowId,
+        index: tab.index + 1,
+        url: url,
+        active: true,
+        openerTabId: tab.id
+      },
+      callback
+    );
+    if (promise != undefined && promise != null) {
+      promise.then(callback);
+    }
   }
 });

extension/src/common/data.ts

@@ -530,6 +530,7 @@ export class DocumentObservations {
     this.sources = [];
     this.primaryTopic = "";
     this.preemptable = false;
+    this.negotiated = null;
   }
   /**
    * The document's url
@@ -547,6 +548,10 @@ export class DocumentObservations {
    * Flag whether the document can be pre-empted
    */
   preemptable: boolean;
+  /**
+   * Dataset that can be obtained at the document's location through HTTP content negotiation
+   */
+  negotiated: DocumentSourceLinked;
 }
 
 /**
@@ -577,7 +582,8 @@ export function observeContent(
       primaryTopic: primary == null ? "" : primary,
       url: observable.url,
       sources: [source],
-      preemptable: MIME.hasOwnProperty(observable.contentType)
+      preemptable: true,
+      negotiated: null
     };
     return observations;
   } else {
@@ -601,11 +607,15 @@ export function observeContent(
         primary = detectTopicOnlinks(links);
     }
     let sources = detectDataOnLinks(links);
+    let negotiated = sources.find(
+      (source: DocumentSourceLinked) => source.url == observable.url
+    );
     let observations: DocumentObservations = {
       primaryTopic: primary == null || primary == undefined ? "" : primary,
       url: observable.url,
       sources: sources,
-      preemptable: MIME.hasOwnProperty(observable.contentType)
+      preemptable: MIME.hasOwnProperty(observable.contentType),
+      negotiated: negotiated != undefined ? negotiated : null
     };
     return observations;
   }

extension/src/common/messages.ts

@@ -266,3 +266,18 @@ export function updateCurrentCommand(
     payload: command
   });
 }
+
+/**
+ * Activates a tab with negotiated content
+ * @param id The identifier of a tab
+ * @param observations The observations for the document
+ */
+export function activateNegotiated(
+  tabId: number,
+  observations: DocumentObservations
+): void {
+  chrome.tabs.sendMessage(tabId, {
+    requestType: "ActivateNegotiated",
+    payload: observations
+  });
+}

extension/src/content/main.ts

@@ -45,7 +45,7 @@ function sendHead(observation: DocumentObservations): void {
 /**
  * Initializes the LD browser
  */
-function initializeBrowser() {
+function initializeBrowser(): LDBrowser {
   // The application view to use
   let viewer: Viewer = newViewer();
   // The LD browser instance
@@ -64,7 +64,19 @@ function initializeBrowser() {
       browser.setCommand(request.payload);
     }
   });
-  browser.onReachedUri(window.location.href);
+  return browser;
+}
+
+function onActivatedByNegotiated(
+  request: Message<any>,
+  sender: any,
+  sendResponse: (response: any) => void
+) {
+  if (request.requestType == "ActivateNegotiated") {
+    chrome.runtime.onMessage.removeListener(onActivatedByNegotiated);
+    let browser = initializeBrowser();
+    browser.onReachedUri(window.location.href);
+  }
 }
 
 /**
@@ -75,7 +87,13 @@ function main() {
   getObservationsFor(null).then((observation: DocumentObservations) => {
     sendHead(observation);
     if (observation.preemptable) {
-      initializeBrowser();
+      let browser = initializeBrowser();
+      browser.onReachedUri(window.location.href);
+    } else if (
+      observation.negotiated != null &&
+      observation.negotiated != undefined
+    ) {
+      chrome.runtime.onMessage.addListener(onActivatedByNegotiated);
     }
   });
 }